Am Freitag, 14. Dezember 2012, 15:38:29 schrieb Uwe Brauer:
> Hello
> 
> I am desperate: I just tried to de install kde trinity
> and now my sudoers file got deleted, a new generated, but
> I do not any longer belong to this group. That is why
> I cannot use my PC anymore.
> 
> Is re installation the only solution?

no :)
1st: can you log in as root or switch to root account using 'su -' ?
2nd: you can always install a new sudoers file from a live CD as long as your 
file system is not encrypted..

werner